Layered Cathode Active Material for Low-Resistance Li-Ion Transport
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Solution Overview
Problem
Cathode active materials in lithium secondary batteries face high lithium ion conduction resistance and decreased charge and discharge capacity due to the presence of reaction-suppressing portions, leading to side reactions and battery deterioration.
Innovation Solution
A cathode active material with a specific composition and structure, including elements M1 and M2, optimized atomic concentrations, and a layered structure, with elements M1 present on the surface and inside secondary particles, enhancing lithium ion conductivity and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reaction-suppressing portion is provided on the surface of the cathode active material, then side reactions are suppressed, but lithium ion conduction resistance increases and charge/discharge capacity decreases
Solution Approach 1:
The invention applies local quality by creating a dual-zone structure where the surface of secondary particles has a high M1 content (α ≥ 0.6) for reaction suppression, while the interior maintains a balanced M1/M2 ratio (β ≤ 0.20) for high lithium ion conductivity. This spatial differentiation allows each region to optimize its function: the surface protects against side reactions while the interior enables efficient ion transport.
Solution Approach 2:
The invention uses composite materials by combining elements M1 (Nb, W, Mo, Ta, La, B, or P) and M2 (Ni, Co, or Mn) in specific ratios to form a cathode active material with composite properties. The controlled distribution of M1 and M2 creates a material that simultaneously exhibits reaction-suppressing characteristics on the surface and high lithium ion conductivity in the bulk, resolving the contradiction between protection and performance.
2Reliability
If a reaction-suppressing portion is provided on the surface, then battery deterioration is prevented, but lithium ion movement becomes restricted
Solution Approach 1:
The invention resolves this contradiction by applying local quality through spatially differentiated composition: the surface region (α ≥ 0.6) is optimized for preventing battery deterioration through reaction suppression, while the interior region (β ≤ 0.20) is optimized for rapid lithium ion movement. This allows the material to simultaneously achieve protection and fast ion transport without compromise.
Solution Approach 2:
The invention applies dimensionality change by transitioning from a uniform composition to a radially differentiated composition within the particle structure. By controlling the atomic concentration ratios at different radial positions (surface versus interior), the invention creates multiple functional zones within the same material particle, enabling simultaneous optimization of protection and ion transport properties.
3Object-affected harmful factors
If element M1 is concentrated on the surface to suppress reactions, then side reactions decrease, but overall lithium ion conductivity is reduced
Solution Approach 1:
The invention applies local quality by creating a radial concentration gradient of element M1: high concentration at the surface (α ≥ 0.6) for reaction suppression, and controlled concentration in the interior (β ≤ 0.20) for maintaining lithium ion conductivity. This spatially differentiated distribution allows the material to simultaneously achieve both objectives without compromise.
Solution Approach 2:
The invention uses parameter changes by precisely controlling the atomic concentration ratios of elements M1 and M2 at different locations within the particle structure. By adjusting the parameters α (surface ratio) and β (interior ratio) to specific ranges, the invention transforms the material properties to simultaneously exhibit reaction-suppressing behavior at the surface and high ionic conductivity in the bulk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cathode active material ensures smooth lithium ion movement and high discharge capacity by optimizing the distribution of elements M1 and M2, reducing side reactions and improving battery performance.
Implementation Method 1
extraction of lithium ions from the cathode active material into the electrolyte and insertion of lithium ions from the electrolyte into the cathode active material are performed according to charging and discharging of the battery
Implementation Method 2
a compound having excellent lithium ion conductivity is provided on a surface and inside of secondary particles, and in which lithium ions can smoothly move
Data Source
AI summary
A cathode active material for lithium secondary batteries contains secondary particles which are an aggregate of primary particles, in which the cathode active material for lithium secondary batteries has a layered structure, the cathode active material for lithium secondary batteries contains an element M1 and an element M2, the element M1 is at least one element selected from the group consisting of Nb, W, Mo, Ta, La, B, and P, the element M2 is at least one element M2 selected from the group consisting of Ni, Co, and Mn, and (1) and (2) are satisfied.